One of the world’s most influential scientists has warned that climate change could devastate Africa, predicting an increase in catastrophic food shortages.

Prof Gordon Conway, the outgoing chief scientist at the British government’s Department for International Development, and former head of the philanthropic Rockefeller Foundation, said in a scientific paper that the continent is already warming faster than the global average and that people living there can expect more intense droughts, floods and storm surges.

There will be less drinking water, diseases such as malaria will spread and the poorest will be hit the hardest as farmland is damaged in the coming century, Mr. Conway wrote.

“There is already evidence that Africa is warming faster than the global average, with more warm spells and fewer extremely cold days. Northern and southern Africa are likely to become as much as 4C hotter over the next 100 years, and much drier,” he said. Mr. Conway predicts that hunger on the continent could increase dramatically in the short term as droughts and desertification increase, and climate change affects water supplies.

“Projected reductions in crop yields could be as much as 50% by 2020 and 90% by 2100,” the paper said.

Mr. Conway held out some hope that east Africa, presently experiencing its worst drought and food shortages in 20 years, will become wetter.

But he said the widely hoped-for 8-15% increase in African crop yields as a direct result of more CO2 in the atmosphere may fail to materialise.

“The latest analyses of more realistic field trials suggest the benefits of carbon dioxide may be significantly less than initially thought,” he said. Instead, population growth combined with climate change would mean countries face extreme problems growing more food: “We are going to need an awful lot more crop production — 70-100% more food will be needed than we have at present.

“Part of [what is needed] is getting more organic matter into Africa’s soils, which are very depleted, but we also have to improve water availability and produce crops that yield more, and use nitrogen and water more efficiently.” Mr. Conway, now professor of international development at Imperial College London, oversaw a major expansion in the UK government’s support for GM research in developing countries, and said new technologies must be part of the African response to tackling droughts.

“In certain circumstances we will need GM crops because we wont be able to find the gene naturally. GM may be the speediest and most efficient way to increase yields. Drought tolerance is governed by a range of genes. It is a big problem for breeders of [both] GM and ordinary plants,” he said.